John Coxon

Field-aligned currents link the ionosphere to the magnetopause (Region 1) and the ring current (Region 2), and are a key part of the way in which energy is transferred into the ionosphere. We use data from the Active Magnetosphere and Planetary Electrodynamic Response Experiment (AMPERE) to quantify the way in which the field-aligned current densities are distributed in each spatial coordinate, and analyse the implications that this has for the parts of the system likely to see the largest amounts of current. We fit a Tsallis, or q-exponential, distribution to the current densities in spatial coordinate, to generate maps of the probability of field-aligned current densities above certain thresholds in both hemispheres. We discuss this in terms of its ramifications for space weather preparedness.